1. Field of the Invention
The present invention generally relates to facsimile devices, and particularly relates to a paper-stacker device which conveys paper sheets from a paper-ejection tray to a desired stack position when the paper sheets are ejected from a facsimile device.
2. Description of the Related Art
FIG. 1 is an illustrative drawing showing a configuration of a wingless-type facsimile device.
The facsimile device of FIG. 1 includes a housing 1, a photosensitive drum 2, a cleaner 3, a electric-charge unit 4, an optical writing unit 5, a development unit 6, a toner magazine 7, a transfer roller 8, a fixation unit 9, a paper-supply cassette 10, conveyor rollers 11, resist rollers 12, paper-ejection rollers 13, a paper-ejection sensor 14, a paper-ejection tray 15, a paper-supply roller 16, a scanner unit 20, a paper-supply tray 21, a read sensor 22, and a paper-ejection tray 23.
The photosensitive drum 2 includes photosensitive material on a surface thereof. The electric-charge unit 4 electrically charges the photosensitive drum 2 to a predetermined voltage level. The optical-writing unit 5 scans a laser beam on the surface of the photosensitive drum 2. The development unit 6 develops an electrostatic latent image formed on the photosensitive drum 2 so as to create a toner image. The toner magazine 7 supplies toner to the development unit 6. The transfer roller 8 is placed in contact with the surface of the photosensitive drum 2. The fixation unit 9 includes a pressure exerting roller and a heat applying roller. The paper-supply cassette 10 stores paper sheets P, and is detachable from the facsimile device. The conveyor rollers 11, the resist rollers 12, and the paper-ejection rollers 13 convey a paper sheet along a paper-sheet path. The paper-ejection sensor 14 is situated before the paper-ejection rollers 13, and detects a paper sheet. The paper-ejection tray 15 is attached to the housing 1, and receives the paper sheets P ejected by the paper-ejection rollers 13.
The scanner unit 20 reads a document, and effects a conversion into an image signal. The scanner unit 20 conveys a document sheet along a document-sheet path after it is placed on the paper-supply tray 21. The scanner unit 20 uses the read sensor 22 to read the document image, and, then, ejects the document sheet onto the paper-ejection tray 25.
In what follows, operations of the facsimile device of FIG. 1 will be explained with regard to image recording on a paper sheet.
A control unit (not shown) of the facsimile device is connected to another facsimile device or the like on a transmission side via a telephone line when a communication circuit is activated in response to a call from a switch board. The control unit then stores images in an image memory when receiving the images transmitted according to predetermined protocols. Further, the control unit loads one page's worth of image data from the image memory to a page memory, and generates driving signals based on the image data stored in the page memory for the purpose of driving the optical-writing unit 5.
The control unit also controls the photosensitive drum 2 to rotate in a direction shown by an arrow upon a start of receiving the image signals, and charges the photosensitive drum 2 up to a predetermined voltage level by use of the electric-charge unit 4. The optical-writing unit 5 emits a laser beam modulated in accordance with the driving signals from the control unit, and scans the laser beam on the photosensitive drum 2 electrically charged at the predetermined voltage level. This creates an electrostatic latent image on the photosensitive drum 2. In association with the rotation of the photosensitive drum 2, the development unit 6 creates a thin layer of toner on a development roller by using the toner supplied from the toner magazine 7, and selectively applies the toner to the electrostatic latent image on the photosensitive drum 2. This develops the electrostatic latent image, and creates a toner image on the photosensitive drum 2.
Upon a start of creating the toner image on the photosensitive drum 2, the paper-supply roller 16 starts rotating, so that a sheet of paper is taken out from the stack of the paper sheets P stored in the paper-supply cassette 10. This paper sheet is conveyed along the paper-sheet path (not shown), and makes a temporal stop when a front end of the paper sheet touches the resist rollers 12. The resist rollers 12 resume the conveyer operation when a front end of the toner image on the photosensitive drum 2 reaches a predetermined position. The transfer roller 8 transfers the toner image from the photosensitive drum 2 to the paper sheet at a position where the transfer roller 8 and the photosensitive drum 2 clamp the paper sheet therebetween.
The paper sheet having the toner image thereon is separated from the photosensitive drum 2 by a separation blade or the like (not shown), and is supplied to the fixation unit 9. The fixation unit 9 applies heat to the toner image while pressure is applied, thereby fixing the toner image on the paper sheet. The paper sheet is ejected from the housing 1 by the mechanism of the paper-ejection rollers 13, and is stacked on the paper-ejection tray 15.
The control unit of the facsimile device loads one page's worth of image data from the image memory to the page memory one after another, and repeats the above operations for image formation until call the received images are printed on the paper sheets P.
The facsimile device as shown in FIG. 1 is generally called a wingless-type facsimile device. The wingless-type facsimile device is designed to save a floor space by avoiding taking up large spaces for the paper-ejection tray 15, the paper-supply tray 21, and the paper-ejection tray 23. Such a design is a response to an increasing need for a reduction of space that is occupied by the device. The wingless-type facsimile device has the paper-ejection tray 15, the paper-supply tray 21, and the paper-ejection tray 23 designed in such a manner that the vertical projection of these trays onto the floor is contained within the vertical projection of the housing 1. That is, these trays are designed not to protrude from the outer limit of the housing 1 in a horizontal direction.
The facsimile device is supposed to receive transmission on its own in the absence of someone's attendance. When no care is taken for a long time such as during a vacation, however, the paper sheets P may accumulate on the paper-ejection tray 15, while nobody is present to take these paper sheets from the tray. The stack of paper sheets on the paper-ejection tray 15, when excessively accumulated, obstructs the paper ejecting operation of the paper-ejection rollers 13, thereby creating such a problem as paper jamming.
In facsimile devices which are not a wingless type, a paper-ejection tray projecting from the housing of the device may be detached before a long period of no attendance. Then, a cardboard box or the like may be placed on the floor where paper sheets are ejected from the housing of the device. This can easily prevent jamming of the paper sheets at a paper outlet of the device, and, also, can avoid spreading of the paper sheets on the floor. The wingless-type facsimile device, on the other hand, has a relatively small vertical distance between the paper outlet and the paper-ejection tray 15, and it is rather difficult to extend the distance because of limitations imposed by the required size and layout of the housing 1. Because of this, jamming of paper sheets cannot be avoided by preventing the excessively large number of paper sheets from being accumulated on the paper-ejection tray 15.
In order to obviate the above-identified problem, Japanese Patent Laid-open Application No. 7-203118, for example, discloses a facsimile device, which directs paper sheets to a different storage than the storage that is ordinarily used for storing paper sheets when a trouble in paper carrying is detected as in the case of paper jamming. This facsimile device, however, needs to have more than one storage, so that such a configuration cannot be applied to the facsimile device as shown in FIG. 1 since the device of FIG. 1 is designed to place paper sheets on a single paper-ejection tray 15 after ejecting paper from the housing 1.
Accordingly, there is a need for a paper-stacker device which can carry paper sheets from a paper-ejection tray to such a place as to pose no obstruction to subsequently ejected paper sheets, and can be easily installed at a position where the paper-ejection tray of the facsimile device is situated.